(1) Field of the Invention
This invention pertains to computer design. Applicant designates a computer design as one having ordinary skill in the art. Therefore, this application is written so that a computer design would be able to make and use the invention.
This invention is to be used with communication cables; and particularly is used to transfer special circuits for old cable to new cable.
(2) Description of the Prior Art
The normal telephone systems and networks were originally installed for voice communication by "plain old telephones". However, they have now come to be used extensively for special circuits. Some of these special circuits are called "T-circuits". Often, either very high frequency transmissions or high speed data is transmitted by these special circuits.
Whereas, for voice communication an interruption in service for a period of one second might have been tolerated, in the special circuits, a disruption of less than 1/100 of a second might cause serious commercial damage. Also, in many of these special circuits, the circuits are almost continuously in use. Normally, the cable includes many pairs of wire.
With the special circuits, it was not possible to bridge the wires in the customary fashion. I.e., if a pair of wires having considerable length were tapped into the cable, the capacitance of a pair of wires would be so great that the high frequency communication could not be conducted. Also, because of the high frequency, if a parallel path were established and one path were longer than the other, disruption would occur in certain instances because there would be a serious out-of-phase relationship in the high frequency transmission due to the longer length of one of the circuits. These problems are different from the problems that exist when the wires and cables are being used only for "plain old telephone service", i.e., voice communication.
The two wires of a pair are designated in the phone system as the ring and tip. One wire being the ring and one wire being the tip of each pair. It was known that various tests could be made; e.g., the voltage determined between the ring and tip, the ring and ground, and tip and ground. Also, in the absence of voltage, the resistance from ring to tip, ring to ground, and tip to ground could be determined.
Furthermore, equipment existed before this invention to measure the capacitance. The capacitance between the ring and tip could be measured. The standard wire in common use would have a certain capacitance of per thousand feed. Therefore, by measuring the capacitance between ring and tip, a measurement could be obtained of the total length of wire. If the capacitance from ring to ground did not equal the capacitance from tip to ground, this difference indicated that the pair was unbalanced.
Furthermore, it was known, because of certain external conditions, the voltage of the wires would vary on an instantaneous basis. Therefore, for accuracy, no reading should be instantaneous, but the average of multiple readings. Of course with structural devices, such as a volt meter having a needle indicating the volts, the inertia of the physical parts act as to average the reading inasmuch as the change in voltage would be so rapid that the needle could not physically move, but because of inertia, would average the instantaneous values.